Irrigation and Aspiration
Once phacoemulsification of the nucleus has been completed, a plate of soft epinucleus or transitional cortex may rest on the posterior capsule. The surgeon can use the phaco needle to accomplish irrigation and aspiration (I/A) without ultrasound; reduced vacuum and flow settings can be employed to aspirate this material from the capsular fornix or posterior capsule.
The coaxial or bimanual I/A technique can also be used to remove peripheral cortical material. With coaxial cortical removal, the port is rotated toward the equator of the lens capsule, and the cortical material is engaged under low vacuum and stripped to the center of the inflated capsular bag. The surgeon rotates the port so that it is fully visible, and the cortex can be aspirated under greater vacuum. This procedure is repeated until all of the cortex is removed. If the surgeon finds it difficult to reach the subincisional cortex, a 45°, right-angled (90°), or U-shaped (180°) aspiration cannula may be useful.
The I/A functions may also be separated using a bimanual technique in which the aspiration port is introduced through the paracentesis incision while irrigation through a second paracentesis maintains the anterior chamber. The instruments may be interchanged as needed (Video 8-6). An advantage of this technique is that it allows the surgeon to more easily reach the subincisional cortex. A disadvantage is that the anterior chamber may become unstable if the flow rate through the aspiration handpiece outpaces the influx of fluid through the separate irrigation handpiece. This issue can be resolved by either decreasing the aspiration flow rate or increasing the infusion pressure.
Bimanual irrigation and aspiration of cortex. Courtesy of Lisa Park, MD.
Cortex resistant to aspiration can be separated from the capsular bag with OVD (ie, viscodissection) to allow easier access with the I/A handpiece. Another strategy is to postpone removal of residual cortex until after IOL implantation. The implant can be rotated within the capsular bag so the haptics further loosen the cortex. The surgeon must weigh the benefits of attempting to remove small amounts of residual cortex against the risk of damaging the posterior capsule. Very small amounts of retained fine cortical strands may easily be resorbed postoperatively.
The surgeon may then polish the posterior and/or anterior capsule surface to remove residual lens epithelial cells, which contribute to development of postoperative capsular opacification and capsular phimosis. Polishing can be accomplished either with a mechanical polishing instrument or with gentle aspiration using an I/A tip. The surgeon must take care to avoid posterior capsule rupture during this maneuver.
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.